Quenching flame fronts after generation, takes many patterns dictated by the type of flame generation and the particular location of the fuel source after ignition of the flame. For example, within oil or chemical refineries, a possible source for fuel has been identified as open water drains. These structures can become contaminated with volatile fluids such as gasoline, diesel fuel and the like unbeknownst to the refinery personnel. As a result during the occasion of use of open flame generating equipment within the refinery in the vicinity of the drains (such as provided by arc welding equipment), safety requires all drain openings be fortified to prevent exterior flame fronts from entering such drains. These take the form of a series of sand bags overlying a grate covering each drain. Each bag is individually filled for each occasion of use and then emptied after the task has been completed. Since each bag contains about 25 pounds of sand, these endeavors have been found to labor intensive, costly and time consuming to achieve. Additionally, the bags can fail during usage, i.e., rips, tears and the like can occur due to foot and vehicular traffic and can also become contaminated with oil, chemicals and the like during usage which may result in their being classified as hazardous waste under State and Federal laws. Also, there is an additional disadvantage of stowage owing to the bulkiness of the bags absent the sand. Sealing on and about the surfaces adjoining the drain opening may be dislodged as bags are shifted to inspection and re-deployment purposes. While the propagation characteristics of flame fronts as well as methods to retard the spread of the vapor evolved ahead of the front, have been studied by others, no one to our knowledge has combined mechanical and material advantages in the manner taught below.
In the present invention, we have found that in the temperature of the propagating flame front in and about water drains in these circumstances even though within 1 degree of fuel ignition (viz., at 999 degrees F. where fuel ignition is 1,000 degrees F.) at the edge of my cover, are quickly quenched because of shape and construction of our cover, viz., we increase loft and weight of the cover about the drain or vent opening using a weighted chain secured within a series of undulations across the surface of the cover. In that way, while the sealing area of the cover relative to the surface about the drain or vent opening is promoted, there is a proportional reduction in the total area defined by the valleys of the undulations. Such reduction substantially decreases the fuel content available to the flame front. Moreover, since the valleys interconnect in serpentine fashion adjacent to the framing surface to be sealed, that framing surface forms a heat sink relative to the flame front. Moreover due to the serpentine nature of the interconnected valleys, temperature differences can be set up along such serpentining valleys. As a result, the efficiency of conventional and conductional heat transfer between the framing surface and any flame front is surprisingly high. Quenching of the flame, results. In addition, the flame resistant nature of the three sheets that sandwich and retain the weighted chain in position about the drain or vent opening, further reduces fuel content in and about our cover. Where our cover has a contact region whose transverse or lateral dimension encompasses at least six (6) undulations about the drain opening, successful usage has occurred.